The present invention relates, in general, to surgical fastening devices for applying a plurality of surgical fasteners into tissue and, more particularly, to a novel method of attaching a buttress material onto the surgical fastening device for the purpose of creating a reinforced surgical fastener line within tissue.
Many surgical procedures involve the resection of tissue. One such procedure is lung volume reduction, which resects a portion of lung to treat emphysema. One problem encountered during the resection of body tissue, especially in conjunction with the use of staples, is the issue of hemostasis. Certain types of body tissue are more prone to the hemostasis issue such as the thin friable tissue found in the lung, and disease conditions can exacerbate the problems. Mechanical devices such as surgical staplers and linear cutters, both open and endoscopic, are utilized as a means of resecting diseased lung tissue. Staples provide hemostasis in vascular structures, and when applied to lung tissue, provide a good degree of pneumostasis as well. Surgical stapling instruments have a plurality of staples held in multiple staggered rows in a replaceable cartridge and a pair of opposed jaws of which at least one is moveable. The surgical stapling instruments compress the lung tissue between the cartridge and the jaw, and the staples are fired into the compressed tissue in close proximity to the diseased portion of the lung that is to be excised. A cutting blade is passed longitudinally between the innermost rows of formed staples, transecting the tissue. The surgical stapling device is removed from the surgical site, reloaded with another unfired stapling cartridge, and the procedure is repeated until the desired section of the lung is resected and removed. An example of an open linear cutter is given in U.S. Pat. No. 5,415,334 assigned to Ethicon Endo-Surgery, Cincinnati, Ohio on May 16, 1995, which is hereby incorporated herein by reference. An example of an endoscopic linear cutter is given in U.S. Pat. 5,597,107 assigned to Ethicon Endo-Surgery Cincinnati, Ohio on Jan. 28, 1997, which is hereby incorporated herein by reference.
One known problem with using surgical staplers used in this fashion has been the formation of air leaks in the stapled lung tissue. The leaks can occur in the cut line, and/or in the staple holes themselves. Frequently, the diseased lung tissue is thin and friable and can tear at the staples as the lungs re-inflate. These air leaks can be persistent and can extend the hospital stay for a patient by weeks. As a means to alleviate these leakage problems, surgeons reinforce the staple line by applying a buttress or pledget material to the desired stapling site and stapling through the buttress material. The buttress material provides reinforcement to the friable tissue. The tissue is compressed against the staple holes resulting in increased pneumostasis. This reduces the chances of tissue tearing at the staple line, and reduces staple pullout in friable tissue.
These reinforcement materials are typically releasably mounted onto the jaw members of a surgical stapling device such that upon firing, the reinforcement material is stapled to the lung tissue. Optimally the lung tissue is xe2x80x9csandwichedxe2x80x9d between two layers of this reinforcement material. Alternately, buttress materials can be used in a number of other surgical procedures such as but not limited to; an ovarian hysterectomy, a gastric bypass, an anastomosis of intestinal tissue, or any other procedure that can require the reinforcement of a staple line or increased hemostasis in tissue.
Releasably attaching the buttress material to the jaw members of the surgical stapling device presents a special challenge. The buttress material must be fastened securely to the jaws of the surgical stapling device so that it won""t fall off during normal operation, yet must be easily released from the surgical stapling device after the staples are fired. A variety of adhesive and mechanical attachment means are known. Both adhesive and mechanical attachments means are discussed below, and both have their deficiencies.
One example of a device which attaches a buttress material to a linear cutter with an adhesive is described in U.S. Pat. No. 5,441,193 and by Gravener et al. This device attaches buttress materials to a surgical instrument with a biocompatible cyanoacrylate adhesive. The adhesive bonding is applied along the edge portions of the buttress material and dashed lines of perforations are placed within the buttress material (adjacent to the glue line) so that the unglued central portion of buttress material can be torn from the glued edge portions. However, the portions of the buttress material having the adhesive applied thereto are not releasable from the device. As a consequence, removing the buttress from the instrument (after firing) can be especially difficult, as all of the material between the perforations must be torn simultaneously to release the surgical stapling device from tissue.
What is needed was an adhesive that would releasably attach the buttress material to the surgical device in a manner that makes it easier for the surgeon to remove the surgical device from the surgical site after firing. U.S. Pat. No. 5,752,965 by Francis et al. teaches the attaching the buttress material or strips to a surgical stapling device with a releasable adhesive that must be applied just prior to use. An alignment fixture is used to align the pair of buttress strips, adhesive is applied to the exposed surface of each buttress strip, and the jaws of the surgical stapling device are then closed upon the adhesive and buttress strips. When the jaws are opened, the buttress material is attached to the jaw and the cartridge of the surgical stapling device with the tacky liquid adhesive. The tacky liquid adhesive is taught as being composed of hydroxypropylmethyl cellulose, polypropylene glycol, and water. While attaching a buttress material in this manner offered a releasable adhesive, the adhesive effects of the tacky liquid adhesive are temporary. In addition, the attachment process is time consuming, and the attachment step must be repeated for each firing. Lastly, once the tacky adhesive is exposed to air, volatile elements of the adhesive begin to evaporate. This limits the application of this tacky adhesive to just prior to or during surgery.
What is needed is a releasable adhesive that that won""t dry out or degrade over time. Such an adhesive would enable the buttress material to be attached to the surgical stapling device at the manufacturing plant, and would result in both time and cost savings. European patent application EP 1064883A1 by Leslie Hamilton et al. teaches a releasable adhesive of nontoxic bioabsorbable aliphatic ester polymers that are semi-crystalline solids or tacky liquids (of honey-like consistency). The adhesive is characterized by being flowable at body temperatures (37xc2x0 C.) and preferably flowable at room temperatures (25xc2x0 C.). However, the adhesive may become much more fluid at the elevated temperatures (up to 50xc2x0 C.) frequently encountered in trucks, shipping containers, railroad cars, and warehouses. Under the elevated temperature conditions, the adhesive can migrate to other parts of the instrument or instrument packaging and the migration can reduce the strength of the adhesive bond.
As seen from the above discussion, attaching a buttress material to a surgical stapler with an adhesive can present many problems. Mechanical attachment of buttress material to a surgical stapling device is also well known in the art and avoids the issues found with adhesives. Many methods of mechanical attachment exist, and a common one is the placement of a sleeve over the clamping members of the surgical stapling device. The sleeves can be formed from flexible fabric such as buttress material, or can contain a releasable strip of buttress material attached to a different fabric. Many of these sleeves are described in U.S. Pat. No. 5,503,638 by Cooper et al, in U.S. Pat. No. 5,702,409 by Rayburn et al., in U.S. Pat. No. 5,810,855 by Rayburn et al., and in U.S. Pat. No. 5,964,774 by McKean et al.
While sleeves can effectively be used to attach the buttress material to the end effector of the surgical stapling device, sleeves can cause other complications during surgery. For example, if the sleeve is formed from a solid sleeve of buttress material, firing the surgical stapling device staples the buttress and tissue and severs the buttress sleeve and tissue between the staple lines. This action leaves the portions of tissue (on either side of the cut line) attached together by a sheet of buttress material. This requires the surgeon to go in and sever the cut sleeve of buttress to separate the severed tissue, and remove any unwanted portion of the buttress material.
U.S. Pat. 5,902,312 teaches a rigid shell or frame that uses suture to releasably attach the buttress. As the surgical stapling device is fired, the knife severs the suture, releasing the buttress from the frame. However, the surgeon must remove the severed suture from the body. What is needed is a means of releasably attaching a buttress strip onto a surgical stapling device, that remains effective over a long period of time, remains operational at all temperatures that are likely to be encountered by the product, and is easily released from the surgical stapling device.
In accordance with the present invention, there is provided a method for releasing buttress material from a stapling instrument when the buttress is attached to the instrument by an adhesive. The method includes providing stapling instrument comprising first and a second opposed tissue clamping members movable between an open position, for receiving tissue therebetween, and a closed position for stapling tissue therebetween. At least one of the first and second clamping members houses a plurality of staples, and a strip of buttress material is releasably attached to the first tissue clamping member by an adhesive. The method then involves moving the instrument to its open position and inserting tissue between the clamping members. Thereafter, the method involves releasing the buttress material from attachment to the first clamping member by closing the instrument and stapling the buttress material to the tissue. Whereby the movement of the staples breaks the adhesive bond and releases the buttress material from the first clamping member.